1. Field of the Invention
The present invention is directed to a remotely controllable circuit breaker which responds to a remote control signal for closing and opening a breaker contact, and more particularly to such a remotely controllable circuit breaker with an improved arc drive structure for rapid arc extinction.
2. Description of the Prior Art
Remotely controllable circuit breakers are well known in the art to have a set of first and second movable contacts respectively driven by a manual switching mechanism with a contact tripping action and by a remote control signal responsive switch. Unfortunately, the prior circuit breakers with remote control capability have been found to be unsatisfactory for the protection against an arc formed between the separating contacts as well as the resulting arc current. For example, U.S. Pat. No. 4,598,263 discloses to mount an arc chute composed of arc shearing plates along the contact separation path in order to expedite arc extinction by drawing the arc into the arc chute due to electromagnetic repulsion forces developed between first and second contact arms extending parallel to each other and flowing the current therethrough upon the occurrence of the arc. Although this arrangement appears to be effective for rapid arc extinction, it suffers from a problem that the arc current or overcurrent will continue to flow through the second contact arm and the second contact held thereon and may cause undesired contact welding or contact defection thereat. Another prior remotely controllable circuit breaker with arc extinction scheme is disclosed in U.S. Pat. No. 4,604,596. This patent utilizes a bypass conductor which, upon the occurrence of the arc, acts to bypass the overcurrent around the second movable contact arm to protect the second contact from being exposed to such over-current. However, in this patent, there is no scheme for magnetically driving the arc for rapid arc extinction by acting on the arc the electromagnetic repulsion forces. The lack of this magnetic arc drive is due to the difficulty in placing within the structure of the breaker an additional conductor in parallel relation to the first contact arm and in spaced relation thereto close enough to produce the electromagnetic forces of sufficient strength for the arc drive.